Technical Field
Exemplary aspects of the present invention relate to an image forming apparatus and a control method for the image forming apparatus.
Related Art
There are various electrophotographic image forming apparatuses that are known as image forming apparatuses such as copiers, facsimile machines, printers, or multifunction peripherals having two or more copying, printing, and facsimile functions. Such an image forming apparatus performs image forming processes, including formation of an electrostatic latent image on a surface of a photoconductor drum, development of the electrostatic latent image on the photoconductor drum with toner serving as developer, transfer of the developed image to a recording medium (also referred to as paper, transfer paper, recording paper, a sheet, and a recording material) by a transfer device such as an intermediate transfer belt, and fixing of the toner image on the transfer paper by a fixing device using heat and pressure.
Such an image forming apparatus forms a test pattern for image density adjustment on the intermediate transfer belt serving as an image bearer, and detects a toner amount of the test pattern to control image forming conditions. A reflective optical sensor is usually used for the toner amount detection.
In particular, high-speed apparatuses used in the production printing field include a line sensor (or density sensor) capable of detecting image density in a main scanning direction to detect the image density on paper. The image density is detected to maintain consistent image density within a page.
For example, a contact image sensor (CIS) used in a reading unit of a scanner is employed as such a line sensor. The CIS includes an image sensor such as a white light source and a complementary metal oxide semiconductor (CMOS). The CIS can obtain reflectances with respect to the three colors red (R), green (G), and blue (B) as outputs.
In addition, there is a method by which the CIS is arranged on the intermediate transfer belt to calculate a toner adhesion amount (hereinafter, also referred to as an adhesion amount) on the intermediate transfer belt based on the outputs of R, G, and B.